I like to start the fort with a few small rooms, and later repurpose them for other uses.
I tend to hollow out about 300 squares of space (3x 10x10 rooms) on the entrance level. To start with the rooms are 1x farm, 1x piles (to move stuff from the embark wagon inside ASAP) and 1x workshops. Then I’ll start digging downwards and building my more permanent locations. The top floor rooms generally become a farm, barracks and trade depot.
By late game I like to have a floor for: finished goods storage, workshops, a few for workshop input materials, misc storage (food, etc), misc services (dining hall, hospital, etc), then beds. Traditionally I’d have one central giant staircase column, usually like:
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But while that looks nice it’s not very optimal. My new strategy is one staircase every ten blocks (the shift-arrowkey distance) in a grid formation across the entire layout. up/down stairs would be most efficient but I use separated stairs for aesthetics.
Whatever stair layout, I put the more important stuff closer to the center. Noble rooms go on the far outer reaches while craft workshops might not even have a wall & door to the staircase.
After this I have transitioned just once to a further fortress, when I built a new fort a few levels above the magma sea and moved everything down there. I stopped going above ground for anything and build a new entrance zone for the fort to deal with sieges underground. You have problems with caravans not hanging around for too long once they finally get all the way down but there is the massive benefit of efficient magma-based metal production. The hardest part is wood, food and water. You basically have to terraform a level or two of caverns which is just never going to be safe with a large fort. Flying forgotten beasts will regularly decimate your army. On the plus side you can make invading goblins path through forgotten-beast infested caverns to get down to you.
EDIT: oh, my starting items never change these days:
Dwarfs:
1 broker
1 Brewer/Farmer
1 stonecrafter
1 mason
1 woodcutter/carpenter
1 doctor
Items:
7 picks
1 axe
0 anvils
As much unique food as I can afford.
If there’s no trees I remove the axe and woodcutter skill and maybe other stuff to take ~50 wood for the beds + barrels/bins I’ll need before first trade.
